Re: [PATCH 4/8] firmware: qcom: scm: Add support for ARM64 SoCs

Bjorn Andersson
2016-04-22T23:41:11Z

On Fri 22 Apr 15:17 PDT 2016, Andy Gross wrote:

[..]
> diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
[..]
> +
> +/**
> + * struct qcom_scm_desc
> + * @arginfo: Metadata describing the arguments in args[]
> + * @args: The array of arguments for the secure syscall
> + * @res: The values returned by the secure syscall
> + * @extra_args_virt: The buffer containing extra arguments
> + (that don't fit in available registers)
> + * @extra_args_phys: The physical address of the extra arguments

@alloc_size

> + */
> +struct qcom_scm_desc {
> + u32 arginfo;
> + u64 args[MAX_QCOM_SCM_ARGS];
> + struct arm_smccc_res res;
> +
> + /* private */
> + void *extra_args_virt;
> + dma_addr_t extra_args_phys;
> + size_t alloc_size;
> +};
> +
> +static u64 qcom_smccc_convention = -1;
> +static DEFINE_MUTEX(qcom_scm_lock);
> +
> +#define QCOM_SCM_EBUSY_WAIT_MS 30
> +#define QCOM_SCM_EBUSY_MAX_RETRY 20
> +
> +#define N_EXT_QCOM_SCM_ARGS 7
> +#define FIRST_EXT_ARG_IDX 3
> +#define N_REGISTER_ARGS (MAX_QCOM_SCM_ARGS - N_EXT_QCOM_SCM_ARGS + 1)
> +
> +/**
> + * qcom_scm_call() - Invoke a syscall in the secure world
> + * @svc_id: service identifier
> + * @cmd_id: command identifier
> + * @fn_id: The function ID for this syscall
> + * @desc: Descriptor structure containing arguments and return values
> + *
> + * Sends a command to the SCM and waits for the command to finish processing.
> + * This should *only* be called in pre-emptible context.
> + *
> +*/

Extra empty line in comment and odd indentation.

> +static int qcom_scm_call(u32 svc_id, u32 cmd_id, struct qcom_scm_desc *desc)
> +{
> + int arglen = desc->arginfo & 0xf;
> + int ret, retry_count = 0, i;
> + u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
> + u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
> +
> + if (unlikely(arglen > N_REGISTER_ARGS)) {
> + desc->alloc_size = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
> + desc->extra_args_virt =

alloc_size, extra_args_virt and extra_args_phys doesn't seem to outlive
this function, can't they be made local variable?

> + qcom_scm_alloc_buffer(desc->alloc_size,
> + &desc->extra_args_phys,
> + GFP_KERNEL);
> + if (!desc->extra_args_virt)
> + return qcom_scm_remap_error(-ENOMEM);
> +
> + if (qcom_smccc_convention == ARM_SMCCC_SMC_32) {
> + u32 *args = desc->extra_args_virt;
> +
> + for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> + args[i] = desc->args[i + FIRST_EXT_ARG_IDX];
> + } else {
> + u64 *args = desc->extra_args_virt;
> +
> + for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> + args[i] = desc->args[i + FIRST_EXT_ARG_IDX];
> + }
> +
> + x5 = desc->extra_args_phys;
> + }
> +
> + do {
> + mutex_lock(&qcom_scm_lock);
> +
> + cmd = ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL,
> + qcom_smccc_convention,
> + ARM_SMCCC_OWNER_SIP, fn_id);
> +
> + do {
> + arm_smccc_smc(cmd, arglen, desc->args[0], desc->args[1],
> + desc->args[2], x5, 0, 0, &desc->res);
> + } while (desc->res.a0 == QCOM_SCM_INTERRUPTED);
> +
> + mutex_unlock(&qcom_scm_lock);
> +
> + if (desc->res.a0 == QCOM_SCM_V2_EBUSY) {
> + if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
> + break;
> + msleep(QCOM_SCM_EBUSY_WAIT_MS);
> + }
> + } while (desc->res.a0 == QCOM_SCM_V2_EBUSY);
> +
> + if (desc->extra_args_virt)
> + qcom_scm_free_buffer(desc->alloc_size, desc->extra_args_virt,
> + desc->extra_args_phys);
> +
> + if (desc->res.a0 < 0)
> + return qcom_scm_remap_error(ret);
> +
> + return 0;
> +}
>
> /**
> * qcom_scm_set_cold_boot_addr() - Set the cold boot address for cpus
> @@ -50,14 +186,68 @@ int __qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus)
> */
> void __qcom_scm_cpu_power_down(u32 flags)
> {
> + return;

We can't have this empty?

> }
>
> int __qcom_scm_is_call_available(u32 svc_id, u32 cmd_id)
> {
> - return -ENOTSUPP;
> + int ret;
> + struct qcom_scm_desc desc = {0};
> +
> + desc.arginfo = QCOM_SCM_ARGS(1);
> + desc.args[0] = QCOM_SCM_FNID(svc_id, cmd_id) |

Are we not playing the endian game om arm64?

> + (ARM_SMCCC_OWNER_SIP << ARM_SMCCC_OWNER_SHIFT);
> +
> + ret = qcom_scm_call(QCOM_SCM_SVC_INFO, QCOM_IS_CALL_AVAIL_CMD,
> + &desc);
> +
> + if (ret)
> + return ret;
> +
> + return desc.res.a1;

We use the following construct elsewhere in scm:

return ret ? : desc.res.a1;

> }
>
[..]
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 8e1eeb8..7d7b12b 100644
[..]
>
> +static void qcom_scm_init(void)
> +{
> + __qcom_scm_init();
> +}
> +
> static int qcom_scm_probe(struct platform_device *pdev)
> {
> struct qcom_scm *scm;
> @@ -208,6 +213,8 @@ static int qcom_scm_probe(struct platform_device *pdev)
> __scm = scm;
> __scm->dev = &pdev->dev;
>
> + qcom_scm_init();
> +

Why don't you call __qcom_scm_init() directly here?

> return 0;
> }
>
> diff --git a/drivers/firmware/qcom_scm.h b/drivers/firmware/qcom_scm.h
[..]
> +#define QCOM_SCM_V2_EBUSY -12
> #define QCOM_SCM_ENOMEM -5
> #define QCOM_SCM_EOPNOTSUPP -4
> #define QCOM_SCM_EINVAL_ADDR -3
> @@ -56,6 +58,8 @@ static inline int qcom_scm_remap_error(int err)
> return -EOPNOTSUPP;
> case QCOM_SCM_ENOMEM:
> return -ENOMEM;
> + case QCOM_SCM_V2_EBUSY:
> + return err;

I don't think return -ENOMEM is the right thing to do here.

> }
> return -EINVAL;
> }

Regards,
Bjorn